Headphone



FIG. 1 is a perspective view illustrating a new design;

FIG. 2 is a top view of the new design;

FIG. 3 is a front view of the new design;

FIG. 4 is a right side view of the new design;

FIG. 5 is a left side view of the new design;

FIG. 6 is a back view of the new design; and,

FIG. 7 is a bottom view of the new design.

The broken lines form no part of the claimed design. 

The ornamental design for a headphone, as shown and described. 